NASA's New Horizons science team recently wrapped up a three-day rehearsal of the busiest days around the mission's Dec. 31- Jan. 1 flyby of Ultima Thule, a Kuiper Belt object orbiting a billion miles beyond Pluto.

Three billion miles away on the farthest known major planet in our solar system, an ominous, dark storm is shrinking out of existence as seen in pictures of Neptune taken by NASA’s Hubble Space Telescope.